Behavioral states are arranged in a triangle.

<p>A. Each of the 832 states with probability greater than 10% is plotted in two dimensions as in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0059865#pone-0059865-g003" target="_blank">Figure 3</a>. The black line is the smallest polygon that contains all of them (the convex hull). The area of this polygon is 90.5% that of the smallest triangle containing them, significantly greater than that expected if they are not constrained to a triangle (<i>P</i><10⁻⁵). The corresponding figure for a test using all the states, not just those with probability greater than 10%, is 90.8% (<i>P</i><10⁻⁵). B. An interpretation of the triangular state space. We suggest that the locomotive behavioral patterns available to a worm can be any mixture of three archetypal patterns, represented as red, green, and blue circles. Like primary colors, these mix to form a triangle of possibilities.